address/index.php works using only using only address/ starts a download

I have this annoying error that I have a great difficulty in resolving. When I go to the site only using the address or ip I receive the following error (in ie) "file download - Security Warning Do you want to save this file, or find a program online to open it?"
I get the same kind of error no matter which browser I use and I also get the same error from other computers.

It seems that I already had the libapache2-mod-php5 installed. I assume it came along when I installed php5.

How about the httpd.conf file? Is that where these things are configured? I can't seem to find that file (used locate httpd.conf). If I create it, where should I place it? Do I need to configure anything else in order for the apache server to find the httpd.conf file?

I tried navigating to your site's IP address, and it loops through an infinite loop loading over and over again (Firefox used)

Your direct index.php file seems to work fine, so you have PHP installed, I think you need to add a directive in the apache config file (or try to add it using ISP Config - I use 3 not 2 so I am not sure if it exists there or not)

The directive should point your default URL to the index.php (if thats what you want)